@Ayespy:
I couldn't disagree more. It's been a year and a half since I had a browser that could display and handle my email smoothly and proficiently right next to the web page window I was working in, and the slowdown to my workflow is STILL being felt. I need a mail panel I can keep open on the left at all times, so bad I can taste it.
If you don't like email in your browser, you can hide it/not use it. I should not be denied an option, just because you can't understand how it's useful.
Absolutely. I am still trying to get used to Thunderbird (I am using Linux/Ubuntu). I can't even see all my inbox from one folder, lots of unnecessary options and so on. Opera Mail had this "one folder for all inbox", simplicity, maillisting and some other benefits. Also, Opera Mail had RSS reader.
Mail Client didn't cause performance issue in Opera if you didn't use it.

Well overall its a good effort so far and its only a preview so we cannot expect miracles. I hope it becomes a good browser but for now I am back on my Opera 28 all updated which runs like a dream. I am sick of people slagging the Opera browser off when I know most of them haven't even been using the newer versions and basing everything off Opera 15. People shouldn't open their mouths unless they test all the new versions of different browsers like I do. I've used them all PCXFireFox, LawlietFox, TeTe Atlier, Palemoon, Maxthon 4, Vivaldi, Liebao, 360, Slimjet, Sleipnir, Lunascape, Avant, IE11 and more. Right now Opera is head and shoulders above the rest. The bookmarks are a nuisance still but the actually bookmark system put in place works well and its clean etc. I think developers need to take a look at the customization of Maxthon and Slimjet and bring it altogether with maybe other actions. I watched a video by some lame brain who got so excited about the Vivaldi F2 menu showing tabs and the tab previews. This same guy slagged off Opera and I sensed he had never even seen an Opera with a preview since Opera has impressive previews on both the tab and side menus
Now as for the status bar, I personally hate these things because yet again they take up space on the screen. So it would be nice to have access on the main panel or menu to the same options shown on the status bar.
As for the removal of the tabs I could never use that feature as I have at least 30 and upwards tabs open at a time. But I think what is the point in removing tabs when you get no benefit from it such as the layout stays the same. What I mean is simply why don't the browser take advantage of the tabs being removed and give you a bit more web page viewing?
The idea of a pop-out video is another good option and ideally copied from the Maxthon 4 browser since you can pop out the video and pop it back without losing where you were. When you use Popvideo extension on Mozilla browsers you might be half way into a video and then pop-out that video only for it to start from the beginning. So as I say Maxthon 4 is the king of the pop-out video so copy their way of doing things.
I also hated the Vivaldi speed-dials showing up in the bookmarks panel, I ended up thinking it was an error and my bookmarks had somehow doubled so I deleted them and realized I'd deleted the speed-dials. Some kind of separation should be made or Ideally keep the Speed-Dials completely out of the bookmark area.

Yes I always found that option very worthwhile and would like to see it implemented on Vivaldi. The only other way of doing this well other than Maxthon (superior) is on Mozilla using an extension called 'popvideo.'

Yes, on my Debian 8.0 system (i7 32G ram) the window is annoying. It's working differently than the whole system. Please dear developers use, the system's wm. My system is not bringing a window to the top when it focused. Not even when I click inside the windows. Only border and title click brings windows the front, and I like it this way. There are some minor bugs, but I understand it is just a preview. Go Vivaldi!
The black death issue (the program starts with an empty black window):
My way: F11 twice! (Full screen, and back)

@petarp:
Maybe I used strange wording beat Opera and Chrome
I am more questioning the starting point. Start developing another browser on chromium … a bit better than using mozilla Why not starting from scratch or start from where Presto left the game?
1. Presto is not open source. It does not belong to them and nobody can use it. Opera never open source it exactly for that reason, so no clones or forks would be made. So that answers your why.
2. Vivaldi is a team of 30 persons, not hundreds of developers or even thousands like other browsers. No time !!!
3. Nobody would code for a niche engine that only has a couple of users worldwide. Everyone will code for Webkit/Blink. At the end of the day you want a browser that works with your websites. Presto never did.
4. Who is going to give Vivaldi the billions to do it? You will? How much did you pay so far or donated to Vivaldi? You do realize the owner is spending his personal money into this company and so far they had no profits. Be realistic. Its a start-up not a multi-billion company, not even Opera could mass market their own rendering engine, they lost.
5. Why in the world re-invent the wheel. That is dumb. Just use what you have right now.